UVa 714 Copying Books——二分最大值最小化

注意上界在累加时可能超过int范围

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;int m, k;long long a[1000];bool judge(long long x) {    long long sum = 0, cnt = 1;    for (int i = m; i >= 1; i--) {        sum += a[i];        if (sum > x) {            sum = a[i];            cnt++;            if (cnt > k) return false;        }    }    return true;}void output(int ans) {    int gang[1000];    memset(gang, 0, sizeof(gang));    long long sum = 0, cnt = 1;    for (int i = m; i >= 1; i--) {        sum += a[i];        if (sum > ans) {            sum = a[i];            cnt++;            gang[i] = 1;        }        if (k - cnt == i) {            for (; i >= 1; i--) {                gang[i] = 1;            }            break;        }    }    int flag = 0;    for (int i = 1; i <= m; i++) {        if (flag++) printf(" ");        printf("%d", a[i]);        if (gang[i]) printf(" /");    }    printf("\n");}int main(){    int T; scanf("%d", &T);    while (scanf("%d %d", &m, &k) == 2) {        long long L = 0, R = 0;        for (int i = 1; i <= m; i++) {            scanf("%lld", &a[i]);            R += a[i];            if (a[i] > L) L = a[i];        }        while (L <= R) {            long long x = L + (R - L) / 2;            if (judge(x)) R = x - 1;            else L = x + 1;        }        output(L);    }    return 0;}