哈理工oj（acm.hrbust.edu.cn) 1498【bfs】

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

const int INF = INT_MAX;

int que[10000000];
int mem[10000000];

int main()
{
    int f, s, g, u, d;
    while(scanf("%d %d %d %d %d", &f, &s, &g, &u, &d) != EOF) {
        int *fr = que, *ta = que;
        for(int i = 0; i <= f; i++) mem[i] = INF;
        mem[s] = 0;
        *ta++ = s;
        while(fr < ta) {
            int c = *fr++, t, sp;
            sp = mem[c]+1;
            t = c + u;
            if(t<=f && mem[t]>sp) {
                mem[t] = sp;
                *ta++ = t;
            }
            t = c - d;
            if(t>0 && mem[t]>sp) {
                mem[t] = sp;
                *ta++ = t;
            }
            if(mem[g] < INF) break;
        }
        if(mem[g] < INF) printf("%d\n", mem[g]);
        else printf("use the stairs\n");
    }
    return 0;
}