Problem:
There are n processes in a queue. Each process has namei and timei. The round-robin scheduling handles the processes in order. A round-robin scheduler gives each process a quantum (a time slot) and interrupts the process if it is not completed by then. The process is resumed and moved to the end of the queue, then the scheduler handles the next process in the queue.

For example, we have the following queue with the quantum of 100ms.

A(150) - B(80) - C(200) - D(200)

First, process A is handled for 100ms, then the process is moved to the end of the queue with the remaining time (50ms).

B(80) - C(200) - D(200) - A(50)

Next, process B is handled for 80ms. The process is completed with the time stamp of 180ms and removed from the queue.

C(200) - D(200) - A(50)

Your task is to write a program which simulates the round-robin scheduling.

Input

n q

name1 time1

name2 time2

...

namen timen

In the first line the number of processes n and the quantum q are given separated by a single space.

In the following n lines, names and times for the n processes are given. namei and timei are separated by a single space.

Output

For each process, prints its name and the time the process finished in order.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 1000

1 ≤ timei ≤ 50000

1 ≤ length of namei ≤ 10

1 ≤ Sum of timei ≤ 1000000

Sample Input 1

5 100
p1 150
p2 80
p3 200
p4 350
p5 20

Sample Output 1

p2 180
p5 400
p1 450
p3 550
p4 800

Notes

Template in C

Solution in C (judge verdict: Accepted)


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_LENGTH_NAME_STR 11
#define MAX_NUM_PROCESS 100000

/*
 * Process
 */
typedef struct {
    char name[MAX_LENGTH_NAME_STR];
    int timeInfo;
} Process;

void copyProcess(Process * p_out, Process in) {
    strcpy(p_out->name, in.name);
    p_out->timeInfo = in.timeInfo;
}
// scanProcess NO NEED
void printProcess(Process process) {
    printf("%s %d", 
        process.name, 
        process.timeInfo
    );
}


/*
 * ProcessQueue
 */
typedef struct {
    Process * processes;
    int head;
    int tail;
    int length;
} ProcessQueue;

void initalizeProcessQueue(ProcessQueue * p_queue, int length) {
    p_queue->processes = (Process *)malloc(length * sizeof(Process));
    // TODO: ^ dangerous!!
    p_queue->head = 0;
    p_queue->tail = 0;
    p_queue->length = length;
}
//void freeProcessQueue(ProcessQueue * p_queue, int length);

// 0 1 2 3 4 ... length-2 length-1
// (length-1) => 0   // looping back to the beginning
//int loopbackIndexIncrement(int index, int length) {
//    if (index + 1 == length) 
//        index = 0;
//    else 
//        index = index + 1;
//    
//    return index;
//};

int isEmpty(ProcessQueue queue) {
    return (queue.tail == queue.head);
}
void dequeue(Process * p_process, ProcessQueue * p_queue) {
//    Process x;// = p_queue->processes[p_queue->head];
    copyProcess(p_process, p_queue->processes[p_queue->head]);
    
    if (p_queue->head + 1 == p_queue->length) 
        p_queue->head = 0;
    else 
        p_queue->head = p_queue->head + 1;
    
//    return x;
//    // is it safe to return struct with string inside?
}
void enqueue(ProcessQueue * p_queue, Process process) {
//    p_queue->processes[p_queue->tail] = process;
    copyProcess(&p_queue->processes[p_queue->tail], process);
    
    if (p_queue->tail + 1 == p_queue->length) 
        p_queue->tail = 0;
    else 
        p_queue->tail = p_queue->tail + 1;
}


void printProcessQueue(ProcessQueue queue) {
    int iProcesses = queue.head; 
    
//    // there is a special reason for using do ... while
//    // since (queue.head == queue.tail) when there are as many processes as the length of the queue!!
//    // But same case for no process at all...
//    // So should we forbit it or allow it?
//    do {
//        printProcess(queue.processes[iProcesses]);
//        printf(" ");
//
//        if (iProcesses + 1 == queue.length) 
//            iProcesses = 0;
//        else 
//            iProcesses = iProcesses + 1;
//        
//    } while (iProcesses != queue.tail);
    while (iProcesses != queue.tail) { // let's forbit it...
        printProcess(queue.processes[iProcesses]);
        printf(" - ");

        if (iProcesses + 1 == queue.length) 
            iProcesses = 0;
        else 
            iProcesses = iProcesses + 1;
    };
    
    printf("\n");
}

void printProcessQueueNewline(ProcessQueue queue) {
    int iProcesses = queue.head; 
    
    while (iProcesses != queue.tail) {
        printProcess(queue.processes[iProcesses]);
        printf("\n");

        if (iProcesses + 1 == queue.length) 
            iProcesses = 0;
        else 
            iProcesses = iProcesses + 1;
    };
}




int main(int argc, char** argv) {
    // scan nProcesses, quantum
    int nProcesses, quantum, timestamp = 0;
    scanf("%d %d ", &nProcesses, &quantum);
    
    // initalizeProcessQueue
    ProcessQueue queue;
    initalizeProcessQueue(&queue, nProcesses + 1);
    
    // process temp
    Process process;
    
    // scan Processes
    for (int iProcesses = 0; iProcesses < nProcesses; iProcesses++) {
        scanf("%s %d ", process.name, &(process.timeInfo));
        enqueue(&queue, process);
    }
    
    // -------------------------------------------------------------------------
    
    // initalizeProcessQueue
    ProcessQueue completeProcess;
    initalizeProcessQueue(&completeProcess, nProcesses + 1);
    
    // do the magic
    for (;;) {
//        printf("timestamp: %d\n", timestamp);
//        printProcessQueue(queue);
        
        dequeue(&process, &queue);
        
        if (process.timeInfo > quantum) {
            timestamp += quantum;
            
            // throw to the end of queue
            process.timeInfo -= quantum;
            enqueue(&queue, process);
        }
        else {
            timestamp += process.timeInfo;
            
            // completing timestamp: current time
            process.timeInfo = timestamp; 
            enqueue(&completeProcess, process);
            if (isEmpty(queue))
                break;
        }
            
    }
    printProcessQueueNewline(completeProcess);

    return (EXIT_SUCCESS);
}