Trapping Rainwater Problem in C++

#include<iostream>

#include <climits>

using namespace std;

// Trapping Rainwater

int trap(int *heights, int n) {

    int leftMax[20000], rightMax[20000];

    leftMax[0] = heights[0];

    rightMax[n-1] = heights[n-1];

   

    for(int i = 1; i<n; i++) {

        leftMax[i] = max(leftMax[i-1], heights[i-1]);

    }

    for (int i = n-2; i >= 0; i--) {

        rightMax[i] = max(rightMax[i+1], heights[i+1]);

   

    }

    int waterTrapped = 0;

    for(int i = 0; i<n; i++) {

        int currWater = min(leftMax[i], rightMax[i]) - heights[i];

        if(currWater > 0) {

            waterTrapped += currWater;

        }

    }  

   

    cout << "water trapped = " << waterTrapped << endl;;

    return waterTrapped;

}

int main(){

    int heights[7] = {4, 2, 0, 6, 3, 2, 5};

    int n = sizeof(heights) / sizeof(int);

   

    trap(heights, n);

    return 0;

}

OUTPUT-

water trapped = 11