题意：在长n的地方，求能完全能放下的有的面积
思路：先从左到右，然后在从右到左统计每个位置能有的高度，最后再相加就是了
#include#include #include #include using namespace std; const int MAXN = 1000010; const int INF = 0x3f3f3f3f; int a[MAXN],b[MAXN]; int n,h[MAXN]; int main(){ int t; scanf("%d",&t); while (t--){ scanf("%d",&n); for (int i = 1; i <= n; i++) scanf("%d",&a[i]); for (int i = 1; i <= n; i++) scanf("%d",&b[i]); a[0] = b[0] = INF; a[n+1] = b[n+1] = INF; int ah = INF; for (int i = 1; i <= n; i++){ if (a[i-1] > ah) ah = a[i-1]; if (a[i] > ah) ah = a[i]; if (b[i] < ah) ah = b[i]; h[i] = ah; } ah = INF; for (int i = n; i >= 1; i--){ if (a[i+1] > ah) ah = a[i+1]; if (a[i] > ah) ah = a[i]; if (b[i] < ah) ah = b[i]; if (ah < h[i]) h[i] = ah; ah = h[i]; } int ans = 0; for (int i = 1; i <= n; i++) ans += h[i] - a[i]; printf("%d\n",ans); } return 0; }