Commit 630e0ff

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trapping rainwater

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	`1`	`+#include <iostream>`
	`2`	`+#include <vector>`
	`3`	`+`
	`4`	`+using namespace std;`
	`5`	`+`
	`6`	`+int trap(vector<int>& height)`
	`7`	`+{`
	`8`	`+ int n = height.size();`
	`9`	`+ if (n == 0 \|\| n == 1 \|\| n == 2)`
	`10`	`+ return 0;`
	`11`	`+`
	`12`	`+ vector<int> leftMax(n, 0);`
	`13`	`+ vector<int> rightMax(n, 0);`
	`14`	`+`
	`15`	`+ leftMax[0] = height[0];`
	`16`	`+ rightMax[n - 1] = height[n - 1];`
	`17`	`+`
	`18`	`+ for (int i = 1; i < n; i++)`
	`19`	`+ leftMax[i] = max(leftMax[i - 1], height[i]);`
	`20`	`+`
	`21`	`+ for (int i = n - 2; i >= 0; i--)`
	`22`	`+ rightMax[i] = max(rightMax[i + 1], height[i]);`
	`23`	`+`
	`24`	`+ int ans = 0;`
	`25`	`+ for (int i = 1; i <= n - 2; i++) {`
	`26`	`+ ans += max((min(leftMax[i - 1], rightMax[i + 1]) - height[i]), 0);`
	`27`	`+ }`
	`28`	`+ return ans;`
	`29`	`+}`
	`30`	`+`
	`31`	`+int main() {`
	`32`	`+ vector<int> array;`
	`33`	`+`
	`34`	`+ int number;`
	`35`	`+`
	`36`	`+ while (cin >> number) {`
	`37`	`+ array.push_back(number);`
	`38`	`+ }`
	`39`	`+`
	`40`	`+ cout << trap(array) << endl;`
	`41`	`+`
	`42`	`+ return 0;`
	`43`	`+}`

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