Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush
import numpy as np

def main():
    input = sys.stdin.readline
    INF = 10**15
    ans = INF
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    dp = np.array([INF]*N, dtype=int)
    dp[0] = 0

    while heap:
        l, r, c = heappop(heap)
        s = dp[l]
        d = np.where(dp[l+1:r+1] < s+c, dp[l+1:r+1], s+c)
        dp[l+1:r+1] = d
            
    if dp[N-1] == INF:
        return -1
    
    return dp[N-1]

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush

def main():
    input = sys.stdin.readline
    INF = 10**15
    ans = INF
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    front = []
    heappush(front, (0, 0))
    while heap:
        l, r, c = heappop(heap)

        front_ = []
        while front:
            r_, c_ = heappop(front)
            if r_ < l:
                continue
            
            heappush(front_, (r_, c_))
            heappush(front_, (r, c+c_))
            if r == N-1:
                ans = min(ans, c+c_)
        
        front = front_
            
    if ans == INF:
        return -1
    
    return ans

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush

def main():
    input = sys.stdin.readline
    INF = 10**15
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    dp = [INF]*N
    dp[0] = 0
    keys = [0]
    while heap:
        l, r, c = heappop(heap)
        
        s = INF
        for k in keys:
            if k < l or k >= r:
                continue
            s = min(s, dp[k])
        dp[r] = min(dp[r], s+c)
        keys.append(r)
        
    if dp[N-1] == INF:
        return -1
    
    return dp[N-1]

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush

def main():
    input = sys.stdin.readline
    INF = 10**15
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    dp = [INF]*N
    dp[0] = 0
    while heap:
        l, r, c = heappop(heap)
        
        s = min(dp[l:r])
        dp[r] = min(dp[r], s+c)
        
    if dp[N-1] == INF:
        return -1
    
    return dp[N-1]

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush

def main():
    input = sys.stdin.readline
    INF = 10**15
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    dp = [INF]*N
    dp[0] = 0
    while heap:
        l, r, c = heappop(heap)
        
        s = min(dp[l:r])
        dp[r] = min(dp[r], s+c)
        
    if dp[N-1] == INF:
        return -1
    
    return dp[N-1]

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import sys
from heapq import heappop, heappush

def main():
    input = sys.stdin.readline
    INF = 10**15
    N, M = map(int, input().split())
    heap = []
    for _ in range(M):
        l, r, c = map(int, input().split())
        heappush(heap, (l-1, r-1, c))
    
    dp = [INF]*N
    dp[0] = 0
    while heap:
        l, r, c = heappop(heap)
        if dp[l] == INF:
            return -1
        
        for i in range(l+1, r+1):
            dp[i] = min(dp[i], dp[l] + c)
        
    if dp[N-1] == INF:
        return -1
    
    return dp[N-1]

if __name__ == '__main__':
    print(main())

Fixed submission:
import sys
from heapq import heappop, heappush, heapify

def dijkstra(s, t, links):
    """Dijkstra algorism
    s: int, start node.
    t: int, target node.
    links: iterable, link infomation.
           links[i] contains edges from node i: (cost, target_node).

    return int, minimal cost from s node to t node.
    """
    heap = list(links[s])
    heapify(heap)
    visited = set()
    while len(heap) > 0:
        cost, node = heappop(heap)
        if node == t:
            return cost

        if node in visited:
            continue

        visited.add(node)
        for cost2, node2 in links[node]:
            if node2 in visited:
                continue

            heappush(heap, (cost + cost2, node2))

    return -1

def main():
    input = sys.stdin.readline
    N, M = map(int, input().split())
    links = [[] for _ in range(N)]
    for i in range(1, N):
        links[i].append((0, i-1))

    for _ in range(M):
        l, r, c = map(int, input().split())
        links[l-1].append((c, r-1))
    
    return dijkstra(0, N-1, links)
    

if __name__ == '__main__':
    print(main())