UVa 714 - Copying Books(二分查找)

在挑战程序设计竞赛上做过类似的,二分答案判断是否合理。

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#include <cstdio>
#include <stack>
using namespace std;
typedef long long LL;
const int maxn = 510;
LL a[maxn];
stack <LL> p[maxn];
int m,k;
bool ok(LL ans) {
int pos=m,t=k;
while(t--){
LL cur=ans;
while(cur>a[pos]){
cur-=a[pos--];
if(!pos) return true;
}
}
return !pos;
}
int main() {
int t; scanf("%d", &t);
while(t--) {
scanf("%d%d", &m, &k);
LL l = 0, r = 6000000000;
for(int i = 1; i <= m; ++i) scanf("%lld", &a[i]), l = max(l, a[i]);
LL mid = (l + r) / 2;
while(l < r) {
mid = l + (r - l) / 2;
if(ok(mid)){
if(!ok(mid - 1)){--mid; break;}
else r = mid + 1;
}
else l = mid;
}
if(ok(l)) mid = l;
int pos = m;
for(int i = k; i > 0; --i){
while(!p[i].empty()) p[i].pop();
LL t = mid;
while(t >= a[pos] && pos) {
t-=a[pos], p[i].push(a[pos--]);
if(pos < i) break;
}
}
for(int i = 1; i <= k; ++i) {
while(!p[i].empty()){
printf("%lld", p[i].top()), p[i].pop();
if(!p[i].empty()) printf(" ");
}
printf(i == k ? "\n" : " / ");
}
}
return 0;
}

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